The proposed research is designed to achieve a satisfactory representation of the processes involved in recognizing and categorizing verbal and non-verbal materials. An initial series of experiments will use reaction-time measures to investigate the effects of various factors on recognition memory. The results will serve to modify and generalize a model of memory storage and retrieval that has been under development for several years. This model incorporates the various stages involved in recognition; i.e., stimulus encoding, memory search and retrieval, comparison of the internal representation of a stimulus with retrieved information, and the processes involved in arriving at a response decision. Similar experimental methods will be used to explore the information processing capabilities of the separate cerebral hemispheres. Other studies will investigate theories of information transfer between long- and short-term memory. The final series of experiments examine applications of the earlier findings to the understanding of such complex cognitive processes as reading. Here we will focus on developmental influences on perceptual and memory skills with the long-range goal of improving instructional procedures and curriculum design.